宫颈癌放疗中多叶准直器角度改变对放疗过程的影响

目的:探讨设计宫颈癌调强计划时，调整多叶准直器对放疗过程的影响。方法:随机抽取12例宫颈癌患者，在其他各项参数设置一样的情况下，采用系统默认的0度角为对照组，调整角度为观察组，据此两种方案制定放疗计划。在满足临床靶区要求的条件下，比较小肠、膀胱、直肠等重要危及器官受量和治疗时长。结果:对照组靶区适形指数、不均匀指数、子野数目、机器跳数分别为:1.05±0.01、0.76±0.03、246±17、1 472±130，观察组靶区适形指数、不均匀指数、子野数目、机器跳数分别为:1.05±0.01、0.77±0.02、236±8、1 447±114，靶区适形指数比较没有统计学意义（P>0.05），观察组子野数目和机器跳数较对照组减少，且比较具有统计学意义（P<0.05）；调整多叶准直器时与多叶准直器为0度时对比，直肠V30、V40、V50的受照体积平均减少（4.3±1.2）%、（5.1±1.5）%、（2.6±1.1）%，膀胱V30、V40、V50的受照体积平均减少（3.6±1.6）%、（5.3±2.0）%、（1.8±0.8）%；观察组治疗时长较对照组平均减少（51±14）s，治疗时长降低且比较有统计学意义（P<0.05）。结论:设计宫颈癌调强计划时，在满足靶区剂量的前提下，适当调整多叶准直器角度可以在一定程度上降低重要危及器官的受量，同时可以减少治疗时长，降低机器的损耗。

The effects of angle change of multileaf collimator on dose distribution in cervical cancer radiation therapy

Objective:To explore the effect of multileaf collimator adjustment on the radiation therapy process when designing a cervical cancer intensity-modulated radiation therapy(IMRT).Methods:12 cases of cervical cancer patients were randomly selected，when all other parameter settings were equal，the system default 0 degree angle was set as the control group，and adjustable angle was set as the observation group.According to the two programs，radiation therapy plan was made.When the requirements of the clinical target conditions were met，the small intestine，bladder，rectum and other important organs affected by the dose and treatment time were compared.Results:The target conformity index，homogeneity index，segment number，monitor unit of control group were 1.05±0.01，0.76±0.03，246±17，1 472±130.The data of observation group were 1.05±0.01，0.77±0.02，236±8，1 447±114.For conformity index，the control group and the observation group had less difference，and there was no statistical significance for comparison（P>0.05）.For segment number and monitor unit，the observation group was less than the control group，and there was no statistical significance for comparison（P<0.05).Compared with the control group，the average dose of the rectum at the observation group was reduced by （4.3±1.2）%，（5.1±1.5）%，（2.6±1.1）%，and the irradiated dose of bladder V30，V40 and V50 decreased by （3.6±1.6）%，（5.3±2.0）%，（1.8±0.8）%.Irradiation dose of the small intestine changed less，and there was no statistical significance.The treatment duration of the observation group was reduced by （51±14）s compared with the control group，and there was statistical significance（P<0.05).Conclusion:When cervical cancer IMRT plan，was designed under the premise of meeting the target dose，adjust multi-leaf collimator angle properly can reduce the amount of vital organs at risk，at the same time，it can reduce the treatment time and reduce the loss of the machine.